Empty regions are initially either dame or derived territory. marking a stone as dead has the effect of converting dame/derived to known for the region bounded by stones of the opposite color. reanimating dead stones returns its adjacent empty nodes to dame. alive stones adjacent to known territory can not be deanimated.

Each category has a hash attribute in the scorable object. they are divided into colors, where each color of that cat has a B::NodeSet. the cats are named _alive, _dead, _known_terr, _derived_terr, _dame, maybe _seki later. each transanimation initiates a floodfill to discover the boundry of its the region bordered by the opposite color.